Re: MD5 listing format
On Sun, Nov 28, 2021 at 12:57:00PM -0600, David Wright wrote:
> I was taken by surprise by the following output from md5sum:
> $ echo special/*
> special/C:\nppdf32Log\debuglog.txt special/same-contents
> $ md5sum special/*
> \adfc1d2f1b1d6c7fcaa51e857c1a6f68 special/C:\\nppdf32Log\\debuglog.txt
> adfc1d2f1b1d6c7fcaa51e857c1a6f68 special/same-contents
Fun.
> I don't understand why it pollutes the first field in its output.
Well, it doesn't bother to *document* why it does this, so we can only
guess (or source-dive).
> I would have thought it sufficient to mangle the filename if it
> feels it has to (echo doesn't bother).
Perhaps it prepends the \ character to the output line to indicate to
whoever's reading this file (which may be md5sum itself, in --check
mode) that a filename mangling *has occurred* and needs to be accounted
for.
Otherwise, how would the reader know whether the filename is actually
C:\\nppdf32Log\\debuglog.txt
or
C:\nppdf32Log\debuglog.txt
... and, upon further investigation, it turns out md5sum is part of GNU
coreutils. Which means the man page that I've been reading *is not the
documentation*. Fuckers.
In the blighted *info page*, there's this paragraph:
For each FILE, ‘md5sum’ outputs by default, the MD5 checksum, a
space, a flag indicating binary or text input mode, and the file name.
Binary mode is indicated with ‘*’, text mode with ‘ ’ (space). Binary
mode is the default on systems where it’s significant, otherwise text
mode is the default. Without ‘--zero’, if FILE contains a backslash or
newline, the line is started with a backslash, and each problematic
character in the file name is escaped with a backslash, making the
output unambiguous even in the presence of arbitrary file names. If
FILE is omitted or specified as ‘-’, standard input is read.
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